Method and apparatus for dehumidifying air



Jan. 7, 1936. c. R. DOWNS 2,027,094

- METHOD AND APPARATUS FOR DEHUMIDIFYING AIR Filed April 6, 19:54

oooooooooo Patented Jan. 7, .1936

" UNITED. STATES- PATENT OFFICE f METHOD AND APPARATUS FOR DEHUMIDIFYING AIR ' Charles B. Downs, Old Greenwich, Conn., assignor -to Weiss and Downs, Inc., New York, N. Y., a

corporation of New York Application April 6, 1934, Serial No. 119,248.

7 15 Claims. The present invention relates to improvements in the m of controlling the humidity of air or gases to suit the comfort of individuals or to suit the requirements of manufacturing processes and the like.

One object of the invention is to provide an improved method and apparatus for dehumidi-' ying air or other gas to maintain a predetermined moisture content. v

Another object is to make improved provision for temperature control.

The invention'aims especially to improve the chloride liquefied in the beds draining into the pools over which the air flows. I I

The present invention constitutes an improvement over that defined in my prior application Serial Number 672,415, filed May 22, 1933 of which 'this application isa continuation part.

The method of dehumidiflcation with-which the invention is more particularly concemed involves passing air through one or a series of drying zones preferably including a pre-drying zone wherein air is brought into contact with a deliquescent material in liquid phase, and thereai'ter is brought into contact with a drying zone which may consist of a plurality of compartments containing deliquescent material in solid phase. When operating under usual dehumidifying conditions the air must be cooled to counteract theheatl'ng of the air and of thedeliquescent ma-' terial due to the effect of the latent heat of the moisture removed and of the heat resulting from the absorption of the moisture by 'the deliquescent material. The cooling may conveniently be carried out by cooling the deliquescent liquid before the air contacts therewith and by cooling the air by passing the air through suitably designed cooling units between the compartments of solid solution, formed as the solid calcium chloride absorbs moisture, drips from the beds. The air' to be'dried is passed over the surfaces of pools of deliquescent liquid maintained in .the trays and thence through the beds of solid. calcium chloride. The solution is drained separately from the several beds of solid'deliquescent.material onto the uppermost tray of the series.

There are certain advantages in maintaining a circulation of the liquid in the trays. Such 10 circulation can conveniently be maintained by pumping the liquid from beneath the trays to the top tray; There is the further advantage in socirculating the liquid that it -can be caused to tail in a continuous sheet or in'a shower from each tray to the next beneath. thus insuring thorough contact of the air with the liquid. The velocity of the circulation of the liquid and the velocity or the air may be so adjusted thatthe liquid falls in a substantially continuous sheet over the edge of each .tray or in'separate streams, and the air in passing'throush each sheet of liquid is thoroughly contacted tobe cleaned and dehumidifled, the adjustment may be such that liquid is entrained in the air and thrown against as the sides of the casing and even against the lower surfaces of the trays.

jwhen a'ir, still ntaining moisture above-the desired amount passes from the pools into the beds of solid calcium chloride, further moisture is.removed therein with the liberation of heat, and the partially liquefied calcium chloride drips I from each bed separately onto the uppermost tray.

Under certain conditions ofoperation there is a tendency for the outlets through which the concentrated solution from the solid calcium chic-- ride beds drips to become obstructed by the congealing of the concentrated solution; It is to be borne in mind that the solid calcium chloride to in the upper compartments is heated by the absorption of the moisture as well as by the release of the latent heat of the moisture changing irom vapor to liquid; and that the initial liquefaction is a factor of the moisture absorbed from the air and the temperature of the calcium chloride, so that a slight drop in temperature will cause this thick viscous liquid originally formed to congeal instead of flowing away. It may happen, therefore, that the lower portion 0! the operative charge of solid calcium chloride where the airhow is less free is enough cooler than the upper and central part, so that as the liquid solution formed in the central portion of the bed passes downward a part or all 0! it-congeals in the lower in which-.-

',-invention,.

I portion of the charge and around the outlet. This congealing is more likely to occur when the operation of the system is interrupted. This possibility of obstruction during use is increased by the air flowing above the trays and beneath the bottoms .tendency toward a cooler condition oi the lower portion of the charge. While heat may be applied by electrical devices or otherwise, it is usually suilicient and it is simpler to provide means for-transmitting the heat of the upper or central portion of the charge to the lower portion thereof and especially to the position around the outlets. To this end heat transmitting elements may be arranged within the charge and extending from the more active warmer portion 01' the charge to the outlets. v

The various features of the invention will be better understood from a consideration of aparticularillustrative embodiment, for the purpose of winch description reference should be had to the accompanying drawing forming "a part hereof and Figure 1 is a verticallongitudinal sectional view oi. an air conditioningapparatus' embodying the 2-15 a transv rse vertical sectional view taken oh 'thelline 2-2 of 1,

. or heat transmitting Figure 3ris a.details'ectional view showing v element, u Figured is a horizoiital' 'sectional view-of the sametaken-ongtheline H or3,

one

a Figures 5' and ii are respectively sectional and plan view of a niother form of heat transmitting element which'is adapted also'to-fo'rm a supportingelement which tends to prevent clogging of the solidcalcium chloride around the outlets, and,

Eigurei' 7 ,isa iurthermodification showing an electrical resistance heating element. Y Theapparatus shownior the purposes of illustrationc'omprisesa housing formed-tor convenienoe. sections 5, 8, I. The central sec-- .tion .6 is fabricated to provide a seriesoi com- 3, 9, ill for receiving solid calcium hlorlde, the uppermosts ectioni being formed toprovidehoppersi I l2, l3 for feeding reserve charges of calciumichloride to therespective compartments and the lowermost section carrying a series of trays l arranged in cascade and'which receive the deliquescent solution formed in the several compartments and dripping therefrom to the. uppermost tray. At the botto'm of this section a reservoir Iii is provided with a cooling unit II therein for cooling the calcium chloride solution which collects in the reservoir after pa'ssingthrough the trays. Apump i3 is provided to-circulate the calcium chloride solution by pumping it from the reservoir throughthe conduit to one of theuppermost trays, preferably the top tray, as in the illustrated structure.

' Air is circulated through the apparatus from I. theinlet 2| successively over the pools oicalclum [chloride on the trays II, as best shown in Figure 2, either from side to side as specifically illustrated or from end to end of the trays II, and then upward into the chamber and horizontallythrough the compartments 3, 9, l0 filled with solid calcium chloride or the like to the outlet conduit 26. v

Under usual working conditions the air is preterably cooled-to compensate for the heating eflect of the calcium chloride in the compartments 3, 9, III. For this pu pose heat exchange units 29 and 33 are shown as positioned between the compartments to thereby cool the air-and the adiacent beds of solid calcium chloride.

In the heat exchange or cooling units the water or other cooling fluid may pass tlrst to the cooling unit I! and then to the units 29 and 30, this arrangement usually giving a satisfactory order of relative temperatures and permitting the air to be discharged at approximately the same temperature at which it is taken into the apparatus.

To prevent cooling and congealing oi the con- 20 centrated solution of calcium chloride formed in the solid beds means is provided for applying a small amount of heat around the outlets through which the concentrated calcium chloride solution drips from the beds to the traiys l5. As a con-'26 yenient means for this purpose, there are shown heat conducting members 33, which extend up into the body of the solid calcium chloride in each The lower-larger cylindrical portions of these members 33 are threaded and flttedinto threaded flanges 31 which, in turn are secured to the bottom plate 32, but carefully insulated therefrom by heat insulating material 38 interposed between the flange and the plate. The ends of 5 members 33 are spaced-from the plate'32 to prevent the lower ends of the members 33 from being cooled by conduction from the plate 32. I1 desired a sheet of insulating material 3| may be providedalong the bottom of plate :2 to prevent thisplate from being cooled by the air flowing therebeneath. Y

In operation the'heat conducting elements 33 will be maintained substantially at the temperature oLthe solid calcium chloride, or at the temperature of the air passing through thecalcium 4 chloride. Thisheat will be transmitted down to. the outlet which in the particular arrangement shown is through the tubular heat conductin member itself. The lower end of the heat conducting tubular members 33 is shown as cut at an angle with the concave side facing toward the current of air so that. some air is deflected up through the tube. The air below the plate 32 .3 is more moist than that in-the. compartments above the plate and its higher moisture content assists in keeping the drainage hole open by re-. ducing the congelation point of the calcium chloride solution draining therethrough. The proportion oiairsopassedistoosmall toadversely affect the overall drying efllciency of the apparatus. .In any event irrespective oiithe shape of the bottom of the delivery tube, the higher preasure of the air below the platevwfll causessome fliair to flow up through the drainage holes and thereby tend to keep them open.

:In Figures and 6 an alternative form of heat conducting member is illustrated. This bridge member Ill is shown-as formed to extend horizontally through the charge of calcium chloride and downward to and around the outlets 4| through which the calcium chloride solutiondrips. Insulation 42 prevents cooling of the bridge member 40 irom the bottom plate 32. In this form or device the horizontally extending portion tends to support a portion of the cal- .cium chloride thereby to prevent it from packing around the outlets. It will be noted that the heat conducting member 40 is so shaped that it extends over. and therefore supports the calcium chloride above the outlets.

The metal usedito'r the heat conducting members should obviously be. 'one'having sufllcient conductivity for the purpose. Aluminum, copper, or the like may beused, and is preferable lac-- cause of the higher conductivity thereof but or-' dinarily iron or steel is sufliciently efiective.

As an alternative or additional heating means electrical resistance heating units 43 may be arranged at' the outlets as illustrated in Figure '7 and suitably insulated to prevent short circuiting.

ment of my invention in an illustrative way it will be understood that other embodiments may be used or various modifications and changes made in the present embodiment without departing tromthespirit of my invention or the scope of the appended claims.

I claim:

1. In an apparatus for conditioning air by the use 01' calcium chloride. a plurality of trays containing calciumicbloride solution, and a plurality of beds of-solid calcium-chloride, means to cause the air to pass over said trays and through said beds to dehumidify the air, means to drain thematerial liquefied in said beds into said trays and means to maintain the liquefied material infisaid beds adjacent said drainage means above its. point of congelation until mixed with the solution in said trays.

2. In an apparatus for conditioning air by the I use or calcium' 'chloride, a plurality oi trays containing calcium chloride solution, and a pluralityyot beds .-of solid calcium chloride, means to cause the topass over said trays and through said beds to dehumidiry the air, means to cool the air in its passage through the apparatus, meansto drain the material liquefied in said beds into said trays and means to maintain liquefied material in said beds above its point of congelation until mixed with the solution in said trays. 1

3. In an apparatus for conditioning air by the use of calcium chloride, a plurality'ot trays containing calcium chloride solution, and aplurality of separated beds of solid calcium chloride, means to cool the airbetween the beds of calcium chloride, means to cause the air to pass over said trays" and subsequently through said beds to dehumidify the air, means to separately drain the material liquefied in said beds into said trays and heat conducting means to maintain the liquefied material in saidbeds adjacent said drainage means above its point or congelation until mixed with the solution in said trays.

4. In an apparatus for conditioning air by the use of calcium chloride, a plurality of trays containing calcium chloride solution, and a plurality While- I have described a particular embodi of beds of solid calcium chloride, means to cause the air to pass over said trays and through said beds to dehumidify the air, means to cool the air in its passage through the apparatus, openings to drain the material liquefied in said beds into 5 said trays' and means to maintain the drainage openings unobstructed, comprising means to conduct heat to said drainage openings and means to cause air to flow therethrough.

5. In apparatus for dehumidifying air or gas, a compartment for a charge of solid deliquescent material having an air inlet and 'an air exit for the passage of air in contact with the deliquescent material therein, and having an outlet for the discharge or the solution of deliquescent material draining from said solid material and means surrounding said outlets and extending inwardly oi the compartment and into the charge for conducting latent heat oi! condensation o1 moisture developed in the charge to said outlet for inhibiting the cooling of the solution to prevent congealing thereo! before discharge from the solution outlet.

6. In apparatus for dehumidifying air or gas,

draining from said 'solid material and means for applying heat to the solution at the outlet to prevent congealing thereabout.

7. In apparatus for dehumidifying air, a compartment for a charge of solid deliquescent material havingan outlet for liquid solution iormed 85 from the deliquescent material, means for passing air through the compartment in contact with said solid material whereby moisture is withdrawn from the air by the deliquescent'material and heat released and whereby solution or said 0 deliquescent material is formed, and means for conducting said released heat to the outlet to prevent congealing of the solution thereabout.

8. In apparatus for dehumidifying air, a compartment for a charge of solid deliquescent ma- 6 terial having an outlet for liquid solution formed from the deliquescent material, means for passing air through the compartment in contact with said material whereby moisture is withdrawn from the air by the deliquescent material and heat released and whereby solution of said deliquescent material is formed, and a heat conducting element' within the compartment contacting with the deliquescent material within the zone of the flow of air in contact therewith and extending to the outlet to conduct heat thereto.

9. In apparatus for dehumidiiying air, a compartment for a charge of solid deliquescent material having an outlet for liquid solution formed from the deliquescent material, means for passing 00 air through the compartment in contact with said material whereby moisture is withdrawn from the air by the deliquescent material and heat from the deliquescent material, means for passing 1 air through the compartment in contact with said material whereby moisture is withdrawn from the air by the deliquescent material and heat, re-

leased and whereby solution 01 said deliquescent 5 material is formed and heat conducting and supporting element extending from adjacent'the outlet upward into the compartment and relatively horizontally to provide partial support for the deliquescent material to reduce packing thereof.

o 1l.- In apparatus for dehumidifying air, a compartment for solid deliquescent material having a bottom member provided with an outlet for liquid solution, means for. passing air through the compartment and a heat conducting member 5 tor the temperature at said outlet above the solidifying temperature for said liquid solution.

12. The method of conditioning air by the use of calcium chloride, which comprises passing the air in contact-with a solution of calcium chloride 0 and through beds of solid calcium chloride, drain ing the material liquefied in said beds of solid .calcium chloride separately through openings from each bed into the solution of calcium chloride, and causing a portion of the air passing 6 over said solution of calcium chloride toflow through the openings through which the liquefied material flows.

13. The method tit-conditioning air by the use ..of calcium chloride, which comprises passing the 0 over a solution of calcium chloride and through a plurality of beds .of' solid calcium' chloride, cooling ofi the air-between the beds-of cna'riricirs or CORRECTION-I solid calcimnchlom'ide, and draining the liquefied calcium chloride from each solid bed separately into the calcium chloride solution while maintaining the liquefied material in 'thedraiiiagev area above its point of congelation until itis mixed 6 with the calcium chloride solution. I

14. The method. of dehumidiiying airwhich comprises passing the air through a drying zone in contact with a solution of calcium chloride 1 and thereatter'throu'gh theb'ody'oiabed of 10 solid calcium chloride constituting a second drying zone, draining the calcium chloride solution formed by deliquescence from the solid calcium chloride into the-liquid zone through openings in the bottonnot the-second and IS applying heat at said peninss of said second drying zone 'to maintainthe solution above the congealing tempera 15. The method of deh mldfl'yins airwhich comprises passing the a drying tone 20" in contact with a solution oi chloride and thereafter through a in contact with solid calcium chloride, thereby by deliquescence of the. calcium chloride, draining the calcium chloride-solution formed by del- 25 iquescence from the solid calcium chloride into the liquid zone and heat to the area of the outlet which the solution Passes to maintain the sameabove the-consealing point of the Solution;

. It isj'h-ere'by .jQ r-ti fied that error appears in the printed ."s'pet: fiioation of the fabov j umbered *p atent requiring correction as "follows: i-iijst 'colui' in ,flinje' 157c1aim 11, after "for" -insert-mai=ntaining; and. that the said Letters Patent should be read with'this correction therein the" samemay c'onifo rn itothe reoord oifthe case in (the Patento iffioeii Signedand; -se'aled ".this,-11th day of- February,- A.- D. 1936: 1 Leslie Frazer-=1 Seal 1' Acting Commissioner of Batfent aQ air through the compartment in contact with said material whereby moisture is withdrawn from the air by the deliquescent material and heat, re-

leased and whereby solution 01 said deliquescent 5 material is formed and heat conducting and supporting element extending from adjacent'the outlet upward into the compartment and relatively horizontally to provide partial support for the deliquescent material to reduce packing thereof.

o 1l.- In apparatus for dehumidifying air, a compartment for solid deliquescent material having a bottom member provided with an outlet for liquid solution, means for. passing air through the compartment and a heat conducting member 5 tor the temperature at said outlet above the solidifying temperature for said liquid solution.

12. The method of conditioning air by the use of calcium chloride, which comprises passing the air in contact-with a solution of calcium chloride 0 and through beds of solid calcium chloride, drain ing the material liquefied in said beds of solid .calcium chloride separately through openings from each bed into the solution of calcium chloride, and causing a portion of the air passing 6 over said solution of calcium chloride toflow through the openings through which the liquefied material flows.

13. The method tit-conditioning air by the use ..of calcium chloride, which comprises passing the 0 over a solution of calcium chloride and through a plurality of beds .of' solid calcium' chloride, cooling ofi the air-between the beds-of cna'riricirs or CORRECTION-I solid calcimnchlom'ide, and draining the liquefied calcium chloride from each solid bed separately into the calcium chloride solution while maintaining the liquefied material in 'thedraiiiagev area above its point of congelation until itis mixed 6 with the calcium chloride solution. I

14. The method. of dehumidiiying airwhich comprises passing the air through a drying zone in contact with a solution of calcium chloride 1 and thereatter'throu'gh theb'ody'oiabed of 10 solid calcium chloride constituting a second drying zone, draining the calcium chloride solution formed by deliquescence from the solid calcium chloride into the-liquid zone through openings in the bottonnot the-second and IS applying heat at said peninss of said second drying zone 'to maintainthe solution above the congealing tempera 15. The method of deh mldfl'yins airwhich comprises passing the a drying tone 20" in contact with a solution oi chloride and thereafter through a in contact with solid calcium chloride, thereby by deliquescence of the. calcium chloride, draining the calcium chloride-solution formed by del- 25 iquescence from the solid calcium chloride into the liquid zone and heat to the area of the outlet which the solution Passes to maintain the sameabove the-consealing point of the Solution;

. It isj'h-ere'by .jQ r-ti fied that error appears in the printed ."s'pet: fiioation of the fabov j umbered *p atent requiring correction as "follows: i-iijst 'colui' in ,flinje' 157c1aim 11, after "for" -insert-mai=ntaining; and. that the said Letters Patent should be read with'this correction therein the" samemay c'onifo rn itothe reoord oifthe case in (the Patento iffioeii Signedand; -se'aled ".this,-11th day of- February,- A.- D. 1936: 1 Leslie Frazer-=1 Seal 1' Acting Commissioner of Batfent aQ 

